There are a number of circumstances where an apparatus for concurrently applying a plurality of strips of an adhesive can be advantageously employed. For example, the construction of roofs for commercial and industrial buildings typically involves, as a first step, installing a corrugated steel decking having alternating peaks, also called ribs, and valleys, also called flutes. Thereafter, one or more layers of an insulating material are placed over the decking. Finally, one or more layers of a waterproof covering or membrane are placed over the insulating material. The membrane may be made of various materials, such as polymeric materials including EPDM (ethylene propylene diene M-rubber), TPO (thermoplastic polyolefin), as well as asphaltic or bitumen based materials.
Conventionally, adhesives are used to secure the various layers of roofing materials to the steel deck to form a unitary covering for the roof. One adhesive composition used to adhere the layers of roofing materials together includes polyurethane. Conventional polyurethane adhesives oftentimes include two separate parts that are mixed by an applicator just prior to being applied onto the surface of the roof deck. The two parts include an isocyanate blend and a simple polyol blend. Upon mixing, the isocyanate blend reacts or crosslinks with the simple polyol blend to form the polyurethane adhesive.
Many roofs may be quite large encompassing many square feet and, in some instances, the roofs may cover several acres. Taking into account the sizes of the roofs that can be involved and the fact that several layers of roofing materials typically are applied, it is highly desirable that an apparatus be available that can rapidly apply large volumes of the polyurethane adhesive to a relatively wide section of a roof, while being easy to operate and control.